Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish readOnlyHint, openWorldHint, idempotentHint, and destructiveHint as safe. The description adds significant value beyond that by disclosing the $0.001 USDC cost, the byte-identical REST endpoint, and the exact content of the response, which makes the tool's behavior concrete and predictable.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, each carrying non-redundant information: the purpose and returned fields, the cost, and the exact endpoint equivalence. The description is front-loaded with the most important purpose information and contains no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only list tool with two optional parameters and an output schema, the description is complete: it tells the agent what is returned, how it is ranked, what it costs, and what API it mirrors. Nothing required to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds some color by tying 'order' to the venue's own liquidity/volume field, but it does not define allowed values or formats beyond the schema. The 'limit=20' in the endpoint example is a concrete sample rather than an override of the schema's default of 10, though it could be slightly clearer.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description identifies the resource (open Polymarket prediction markets), the ranking dimension (the venue's own 24h volume or liquidity), and the returned fields. It reads as a fragment rather than an explicit verb phrase like 'List' or 'Get', and it does not explicitly name its sibling distinction, but the plural 'markets' plus the ranking context separates it from market_poly_market_detail and market_poly_tags.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context for when this tool is appropriate: retrieving active Polymarket prediction markets sorted by the venue's own volume or liquidity, with an exact GET endpoint equivalent. It does not explicitly state when not to use it or point to alternative sibling tools, so it stops short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.